Disk trimmer



Feb. 20, 1940. F, 0, ALBERTSON f l 2,190,758

DISK TRIMMER Filed Feb. 7, 1958 4 Sheets-Sheet ,l

23291 .10. J/@MW @lie/KZ@ @gf/"Zugv Feb. 20, 1940. F. o. ALEERTSDN DISKTRIMMER 4 Sheets-Sheet 2 Filed Feb. 7, 1938 Feb. 20, 1940. F. o.ALBER'rsoN 2,190,758A DISK TRIMMER Filed Feb. 7, 195s sheets-sheet sInvero? (921 jf/"zlzg QJLZ 61275017@ M Feb. 20, 1940. o. N EsER-rscm2,190,758

DISK TRIMMER v Filed Feb. 7. 1938 4 Sheets-Sheet 4 latente Feb, 20,1940

DISK `'IRIMMER y liransfO.` Albertson, Sioux City, Iowa, assignor to lAlbertson `t Company, Inc., Sioux City, Iowa,

a corporation of Iowa f Application February '1, 193s, serai No. 189,037

comms. (01.16443) Thel present invention relates to` disk triml mers,and is particularly concernedwith devices i `for trimmingoff` they edgesof the abrasive disks` t of the type which are used on electric sandingmachines. w l" Such abrasive disks are usually subjectedto thejmost`wear at that area of the` disk` which is adjacent thev outer edge ofthe face, and it is that portionof thedisk which becomes iilled withdirt and other foreign material, such as paint, during the` abradingoperation. Consequently,

the abrasive disks may be used over and over again by applying them toasmaller `supporting pad, after trimming oit the worn edge.

, One of the objects of the inventionisthe proo vision o an improved`tool by means of `which the used portionl'of an abrasive disk mayybecut o1.` f Another object of the invention is` the provision of animproved` cutting tool by means of which t, the parts of an abrasivedisk maybe trimmedoff and thedisk put in proper position for usegon asmaller `,supporting pad. t .t

1 Another object `of the invention is the provision of animproved diskcutting tool of the `class de` scribed which is simple,` sturdy,economical, and

` Wadaptedto the quick and clean cutting or trim-l `-`vming `of abrasivedisks with a minimum amount Y `of` effortnin` order toyutilize fully allof the area ,30" t.,

ofthe abrasive' material. 1 o

Another object ofthe nventionis `the provision "of an improved disktrimmer which is` provided` with, forma-multiplying means lforincreasing `the pressure applied to thetrimmer,` whereby the disk` maybe trimmed more quickly and easily. Another objectof theinvention is theprovision "of an improved trimmer which has provision for `supportingdisks not only of different sizes,` but .1 having different sizesof`centrally located shaft holes. t M o t Another `object of the` inventionis ythe provision of anyimproved diskv trimmer] which may be adjustedtostandard sizes of disksjvery quickly and to variousother intermediatesizes, with a mini- `mum number` of manual operations.N4

y Another object is `the provision of an improved method of trimmingabrasive disksut Other objects andadvantageswill be apparent ofrom thefollowing descriptionand-rthe ccom.. t

l y panying drawings, in which similar characters of t refereneeindicatesimilar parts throughoutthe several views.

Referring `to the four sheets of drawings accompanying. this`specication,

`1 is a top planview of a disk cutter constructed according tothepresent invention;

Fig. 2 is a side elevational View of the disk cutter;` 1 t 1 Fig. 3 is afull size vertical sectional View; taken through the mechanism of thecutter on the plane of the line 3-3 'of Fig. l, looking in the directionof the arrows;` i t Fig. 4 is a sectional View, taken on the plane ofthe line ll--d` of Fig. `3, looking in the `direction of thearrows;

5 is a vertical sectional view, takenwon `the plane` of the line 5-5 ofFig.` 2,( looking in the direction of the arrows, showing theydetails ofconstructionv of the disk supporting trunnion;

Fig. 6 is a viewA similarto Fig. 5, `with the parts of kthe'lattermechanism in a different position;

direction of the arrows; 1; i i

Fig. y`8wis a diagrammatic illustration'ofone form of diskfor whichthedisk cutter is adapted; Fig. 9 is a similar ,viewofanother form ofdisk;`

of an abrasive disk which has been subjected to `the action of thetrimmer, but from which the used portion has not yet been broken off.`The present invention is an improvement over my prior Patent` No.2,066,381, issued January l 5, 1937,

Referring to Figs. 1-3, 2li` indicates in its en` Fig. 10 is afragmentary plan view of a `portion l," i

1 i Fig. 7 is a vertical sectionalview, takenon the plane `of the line1-1 of Fig. 3, looking in the so' i tirety my improved disk trimmer,which is shown in `connection with an abrasive disk 2l, andis carried bya support 22, such vas a table or work bench. lThe trimmer 20 has itsmechanism4 sup-l ported upon a castmetal body 23, which `may besubstantially 'rectangular in plan, as shown in Fig. 1, andsubstantiallyrectangular in elevation at each of, the sides thereof, as shown inFigs.

` yto 2`and7., t n The supporting casting or body 2,3,has a pair of sidewa1ls2425,`which are provided with 1at` erally Yextending attachingflanges 26,121` having` Y apertures 28 for receiving` the wood screws29, which secure the trimmer to the table` or `bench 22; Thcbdy `2,3alsohas a top wall 30,`and referring to Fig. 2, a lett end wall 3l andright end wal132.` 't

The leftA end wall `(see Fig. `3.) extendsdown to the `point 33. The topwall is thickened from 33 to `a vertically extending aperture `34 toprovide material forming a bearing 35 for a cutter shaft"36., `The body`is reinforced adjacent the slot 34` b`y` a depending rib 31.` l The slotor aperture 34` Lextendsfronithe bottom to thetop of the body andprovides space for the location of the cutter 36, which is carried bythe shaft 35.

The shaft 36 comprises an elongated cylindrical member of such size astobe rotatably mounted in the bearing bore 35. At its right end it isprovided With a reduced vsquared portion 3&3 for receiving the cutter3S; which has a squared aperture lli of the same size. At this end theshaft 36 also has a reduced cylindrical ,threaded portion 4l forreceiving a nut 42, which clamps the cutterv 38 in place. f

Washers 43, 44 are preferably disposed on each",y side of the cuttertoserve as thrust bearings and tospace the cutter body slightly fromithevvallofH the slot 34.

The cutter 38 comprisesahardened steelmem'- ber of substantiallycircular form, which is provided on its periphery (Fig. '7.) ,with amultiplicity of inwardly extending V-shaped slots 45. These slots may bespacedin a random mannerto pro-j. videiknife edge formations 4@ ofdiierentlength with reSpect to the direction of the Iperiphery of thedisk. The cutter ,(E'ig. 3l is SubStantallyIat and of uniform thicknessover its central portion, extending to aradius' outside of the washers143,

V vlill; that "is, to the point'fil; but from the point rthe annularshoulder 54..

The crank 52 may consist of a metal bar which 4'! to the edge ofthecutter, the cutter is .tapered as at 48 to a sharp knife edge 46.

The vleft end of the shaft 36 (FigiA 'Ssuppcrts a spacing sleeve #i9 andhas a reduced threaded portion 5l! for receivingthe'threaded nut '5|'-and the 'crank 52, which has a threaded 'bore The nut-5I is, therefore,adapted' to actl asj-a lock Washer for securing the crank 52j againstmaybe slightly offset, if desired,' intermediatejits length, andWhich-'is provided with the threaded bore 53 at one end and with asmaller threaded borev 55 adjacent the other end. 'Ih`e s malle` rthreaded bore 55 receives the threaded end'of a knob-supporting pin56,1the .head Fplfof the'pin, l retaining the knob 5? on the 'crank'armV5l). Thus the'cutter 58 is mounted to rotate with the shaftv 36, andthe crank 52 `is vadapted to rotate the shaft and cutter for a purposefurther to be ydejg scribed. The rear Wall 32 of the trimmer body` is v.provided with a centrally located horizontally' ex:

tending bore SU for receiving the cylindrical-.end

6l of a .guide bar 62, the restof the guide'bar" being. non-circular yorl rectangular in .crosssection, asshown inFig. 5. A set screw 63threaded into a' suitable threaded bore in theibottom .of the vvall4 32is adapted .to secure the bar 62 tothe Wall at substantially rightangles thereto'. 'Ihe-gui1.'er bar 62 may'jbe vprovided at 4its outerYend With Lan additional sup`- v porting foot in the form of ascrewmbolt VEidtvvl'iich is threaded into a threaded bore 65 in the.bottom ofthe guide bar at ,its extremeend',` the' screw bolt Sli havingitsv headV in engagement witha spacer sleeve 66. The lengthof the screw'l is the guide bar 62." l The guide bar 62 `may be providedwi-thone or more stop members in the iorm o ffscrevv'bolts 6l, 68, which arelocated at ythe proper position for the slider ,69 for predetermined;sizesof disks. For example, the stop 61 is at the properposition for aseven inch diskgwhilelstop d8 vislin the proper position for-thesliderfora i'lve inch disk, and when the slider 63 is against the wal l ;32;it is inproperposition for. a, three inch disk,v .The numbers 3, 5and7thusappearon `the top of the then Y.such that .itaidsin supporting" thatend o f guide bar s2 adjacent the stops. Naturally, the

screw y68 must be removed vbefore the slider can l be moved overto thethree inchposition against the Wall 32. l

The lslider may also be located at ,any intermediate position or anyposition beyond the stop 6l tothe end of the bar for intermediate sizesof abrasive disks, or for larger disks.

f The-slider supports a shaft or trunnion il) extending upward at rightangles to the bar 52.

Slider 69 may consist of a block of metal, such` :fasi steel, which isprovided with a rectangular .aperture ll adapted to slidably receivevvthe rec- ,tangular or square bar 62. Thus the slider Sli is slidalolyvmounted on the har t2, but is prevented }'rom'.rotatng,:and is heldAupright position. =-"-'Ilheslider lidmay be secured'in any predeter-.mined position by. .means `of a thumb screw '89 which is threaded intoa threaded bore @il in slider 69,-.' a'ndthe end of which engages thebar 62.

At its upper side itis provided with a cylindric jbore 72 whichis,adapted'tonreceive vv'ith a tigntfnctipaal' nt the reduced cylindricalend ie ofthe-stubshears. missies shaft 'is is formed with'fa middlecylindrical portion' 'lli and an end cylindrical head l5 of larger size,thus providing theannular shoulder it :for retaining a sleevell onthefshait'v le., The larger vcylindrical portionA l'l5 servesas'atrurinion or'support3for rotatably supporting theablfasive disk 2l,having a relatively small .central aperture it. I'he'present device is,however, adaptedto be used for'sup'port'ing other abrasive disks ld,having' 'a largerfcentrally located apertureV Bil, as s "j'lhesleevefjl'i isa metal member formed with." I a cylindrical body 8lhaving afcentrally located' bore 82 for rotating andsliding movement onthe shaft 1B, The body '3l has a 'pair of `transverse slots, the slqtjlbeing relatively shallow, 'while the slotl sglisatlfright anglesthereto, and is a.; y

relatively deep slot.

A metal pin @projects laterally` from each lsider of the shaft'lllfandis xedly secured `by al fri'cf tional lit` an aperture in theshait l insuch pesitionthatit Will-registerfwith either of the slots 83, BAW/Thebody Si `of lsleeve i'lhas a revy dueedeyiindrical porties et which' isals@v adapt,-v

edjto servev as a trunnionf oran abrasive disk 179.

cylindrical-portieri 86. l When ,the sleeve ll' Vis in the position'cFig.v 3, the pin'li.` is' in theslot dit and the proportions andlocation of .pin and slot are such that the up'-,`

y having anenlarged apertures@ iitting about the perv end Blof sleeve'il' is approximately on the same plane as the upper 'edge or cuttingedgeofA i the cutter 3.8l (Fig. 3). Thus the endfl voi sleeve 'l1 servesas a support for determining .the proper level of the abrasive disk.`

' When the sleeve 'il is lifted so thatthe pin 'emerges from slo't 855,the sleevell` may then be rotated until slot d3 registersvvitli pin'ii,and

` dropped in thatlposinon.' The sleeve is tnen'in the'positionof'l'ig.63 and thecylindrical portion.`

86 of the sleeve serves asa trunn'ion for the disks (Fig. 9) havingthe-:larger haies the disk being supported upon the annular vshoulder88.

i Theannular shoulder *8871s then on a level with theluplOC-rr edge'zof.the cutter 33. U i

Theybodyd of the .disk trimmer isfprovided` with a pair oi"A upwardlyprojecting. bearing lugs 9i, 92 (see Fig. 1), Figj2 of Whicha-reprovided with registeringaperturesy 93 for receiving a bearing pin 94;Whioh .may be riveted.V in rvplace, `or

which may have a tight frictional t in the apertures 93.

The pivot pin 94 pivotally supports a forcemultiplying pressure leverwhich has its left end (Fig. 3) mounted on the pin 94. The lever 95 maycomprise a cast metal member which is provided with a substantiallyrectangular slot 96 on its lower side, and with a handle 91 which iselongated and extends over both the abrasive disks 2 I.

The lever 95 is provided with a longitudinally extending bore 98, whichis in alignment with another threaded bore 99 located at the oppositeside of the slot 96. A screw bolt |99 has its head `|9| countersunk incounterbore |92 and has its threaded end threaded into the vertical bore99.

The screw bolt |99 rotatably supports a soft steel roller |93 which hasan outer cylindrical surface |94 located to engage the top of anabrasive disk 2| when the disk `is engaging the cutter 38. The slot 96is of suficientwidth to receive not only the roller |93, but apluralityof washers |95, and the washers |95 may be used to change the positionof the roller |93 when the surface ofthe roller |93 immediately abovethe cutter 38 has become worn. After long service a groove willeventually wear in the roller |93 above the cutter 38 and retard thecutting. Then one of the spacer washers |95 may be moved'over to theright of the cutter |93, by taking out the screw bolt |99 and replacingit, and then a new surface on the roller |93 will be in position abovethe cutter 39.

The lever 95 has an end surface |96 adapted to serve as a stop, engagingthe sleeve 49 or end of crank arm 59 when the lever 95 is pivoted fromthe full line position of Fig. 3 to the dotted line position of Fig. 3.In the dotted line position of Fig. 3 the stop surface 99 is supportingthe lever 95, which moves far enough so that its weight is shifted fromthe right side of the pivot pin 94 to the left side thereof inFig. 3.Thus the lever 95 is self-supporting in the dotted line position,

which it assumes when the operator is placing or removing the abrasivedisk 2|.

The operation of the present disk trimmer is as follows: l

'I'he sleeve 11 is adjusted to the position of Fig. 5 or Fig. 6,depending upon the size of hole in the abrasive disk 2| or 19. Assumingthat disk 2|, with the smaller hole, is to be used, sleeve 'l1 is intheposition of Fig. 3; and with the lever `95 in the dotted line positionthe disk 2| may be placed upon the trunnion 15. The slider 99 may thenbe adjusted by loosening the thumb screw 89 and sliding the slider alongthe bar 92 until `the position of the edge of the disk 2|' with respectto the cutter is as desired; that is, the disk ismoved until it isobserved that the cutter will trim off the desiredamount, which, wouldbe the worn or lled portion of the abrasive disk.

The disk is applied to the trimmer with its abrasive side up, so thatthe cutter engages `the smooth or paper side of the abrasive disk 2|.The roller |93 engages the abrasive side of the disk.

The operator then applies pressure to the roller |93, which in turnengages the abrasive disk and forces it against the cutter 38. Thispressure is applied by pushing down on the hand lever 95. A considerableamount of pressure may then be applied with a minimum amount of effort,due to the location of the cutter adjacent the point of pvot 94, and dueto the length of the hand lever 95. i

With the pressure thus applied, the operator rotates the crank 52 withhis other hand by means of knob 58, thus also rotating the shaft 36 andthe cutter 38. The cutter teeth or knives 9 bite into the ber or basematerial of which the abrasive disk is constructed and serve to causethe abrasive disk to rotate on the trunnion 'l5 as the cutter rotates,the teeth in effect forming their own interlockingdepressions inthebottom side of the abrasive disk.

Depending upon the thickness and toughness of the abrasive disk backing,the disk may be r0- tated once, twice, or more times, the knives 46 scutting in more deeply on each successive rotation, but it is generallyonly necessary to eiect one rotation of the abrasive disk 2|, duringwhich the knives will produce aplurality of spaced cuts in the lowerside of the abrasive disk, as shown in Fig. l0. These spaced cutspractically go through the backing and abrasive facing of` the, disk 2|,but the trimmed edge may still be retained on the abrasive disk and maythen be removed by a tearing operation along the dotted and punched line|91 (Fig. l0).

During the rotation of the abrasive disk the roller |93 rotates butserves as a backing for pressing the abrasive disk against the cutter.

The disks may thus be trimmed neatly and cleanly with a minimum amountof effort and again used on a supporting pad of smaller size so as toutilize all `of the area of the abrasive disk down to the smallest size,which is approximately three inches.

Myimproved method of trimming abrasive disks comprises pressing the rearside or backing of an abrasive disk against a knife and cutting in saidrear side of the abrasive disk a plurality of spaced indentatons. 'Thismay be done by feeding the disk to the knife in a rotary direction, andthereafter the trimmed portion may be broken or torn from the disk toeffect a clean cut s `size of abrasive disk and to one or more sizes ofcentrally located abrasive disk apertures. It is adapted to be used fora longer period of time without dulling the cutter, and greater pressuremay be applied tothe disk and cutter with less effort, so that the disksare trimmed much more quickly than by means of the prior art devices.

While I have illustrated a preferred embodiment of my invention, manymodifications may be made without departing from the spirit of theinvention, and I do not wish to be limited to the precise details ofconstruction set forth, but desire to avail myself of all changes withinthe scope of the appended claims.

Having thus described my inventiorn what I claim as new and desire tosecure by Letters Patent of the United States, is:

l. In a trimmer for abrasive disks of the type having a centrallylocated aperture, the combi* nation of a base adapted to be secured to afixed support, said base having a transversely extending bearing and adrive shaft in said bearing, a crank carried by the outer end of saidshaft, and a cutter wheel carried by the opposite end of said shaft andiixedly secured thereto, said cutter wheel having a sharp peripheraledge separated by a plurality of slots forming radially projectingknife-like teeth adapted to engage in the back of a .disk tofformiindentations drive :the ldisk, and ,a support for the fdiskcomprising a guide member carried ,by said baseand projectingsubstantially parallel to said shaft, said guide member being providedwith a slider, and said slider being adapted to be 4received in theaperture of said disk for rotatably supporting the disk, said baseIhaving a pressure lever pivotally mounted thereonabove said shaft,.said pressure lever overhangingsaid trunnion .and being provided with acylindrical pressure roller located above said cutter and rotatablymounted upon a shaft eX- tending substantially parallel to the cuttershaft when the roller is engaging a disk whereby a disk may be locatedon said trunnion, with its abrasive side engaging said roller, and byrotating said crank and pressing downward on said lever said Cutter willdig into the back side of the abrasive disk to f orm indentations andthe teeth of said cutter will drive said disk, causing it to rotateabout said trunnion, said roller forcing said disk against said cutterwithout bringing the cutter into engagement with the abrasive, wherebythe indentations form a circular line about said disk, and the part ofthe disk outside of that line may be broken 01T by the hand, the lengthof said lever being such that suificient force may be applied to therear side of an abrasive disk with the cutter, without forcing thecutter through the abrasive and into engagement with the roller.

2. In a trimmer for abrasive disks of the type having a centrallylocated aperture, the oornbination of a base adapted to be secured to a.fixed support, said base having a transversely extending bearing and adriveshaft in said bearing, a crank carried by the outer end of saidshaft, and a cutter Wheel carried by the opposite end of back of a diskto form indentations and drive v .the disk, and a support for the diskcomprising a guide member carried by said base and projectingsubstantially parallel to said shaft, said guide member being providedwith a slider, and said slider being adapted to be received in theaperture of said disk for rotatably supporting the disk, said basehaving a Vpressure lever pivotally mounted thereon above said shaft,said pressure iever overhanging said trunnion and being provided with acylindrical pressure roller located above said cutterr and rotatablymounted upon a sha-ft extending substantially parallel to the cuttershaft when the roller is engaging a disk whereby a disk may be locatedon said trunnion, with its abrasive side engaging said roller, and byrotating said crank and pressing downward on said lever said cutter willdig into the back side of the abrasive disk to form indentations and theteeth of said cutter will drive said disk, causing it to rotate aboutsaid trunnion, said roller forcing said disk against said cutter withoutbringing the cutter into engagement with the abrasive, whereby theindentations form a circular line about said disk, and the part of thedisk outside of that line may be broken off by the hand, said rollershaft being provided with a plurality of vspacers mounted thereon,whereby the position

